[dpdk-dev] [PATCH 1/4] net/virtio: fix interrupt unregistering for listening socket

[Ilya Maximets]

virtio_user_dev_server_reconnect() is typically called from the
interrupt context while checking the link state:

  vhost_user_update_link_state()
  --> virtio_user_dev_server_reconnect()

Under this conditions callback unregistering always fails.  This means
that listenfd is never unregistered and continue to trigger interrupts.
For example, if second client will try to connect to the same socket,
the server will receive interrupts infinitely because it will not
accept them while listen fd is readable and generates epoll events.

Fix that by moving reconfiguration of interrupts out of the
interrupt context to alarm handler.

'virtio_user_dev_delayed_handler' renamed to
'virtio_user_dev_delayed_disconnect_handler' to better reflect its
purpose.

Additionally improved error logging around interrupt management.

Fixes: bd8f50a45d0f ("net/virtio-user: support server mode")
Cc: stable at dpdk.org

Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
---

CC: Zhiyong Yang <zhiyong.yang at intel.com>

 drivers/net/virtio/virtio_user/vhost_user.c   |  4 +-
 .../net/virtio/virtio_user/virtio_user_dev.c  | 70 ++++++++++++++-----
 .../net/virtio/virtio_user/virtio_user_dev.h  |  2 +-
 3 files changed, 57 insertions(+), 19 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/vhost_user.c b/drivers/net/virtio/virtio_user/vhost_user.c
index f8569f6e6f..25f74c625b 100644
--- a/drivers/net/virtio/virtio_user/vhost_user.c
+++ b/drivers/net/virtio/virtio_user/vhost_user.c
@@ -957,7 +957,9 @@ vhost_user_update_link_state(struct virtio_user_dev *dev)
 			 * of interrupt handling, callback cannot be
 			 * unregistered here, set an alarm to do it.
 			 */
-			rte_eal_alarm_set(1, virtio_user_dev_delayed_handler, (void *)dev);
+			rte_eal_alarm_set(1,
+				virtio_user_dev_delayed_disconnect_handler,
+				(void *)dev);
 		} else {
 			dev->net_status |= VIRTIO_NET_S_LINK_UP;
 		}
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 1b54d55bd8..68cece42d3 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -13,6 +13,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
+#include <rte_alarm.h>
 #include <rte_string_fns.h>
 #include <rte_eal_memconfig.h>
 
@@ -885,7 +886,7 @@ virtio_user_dev_reset_queues_packed(struct rte_eth_dev *eth_dev)
 }
 
 void
-virtio_user_dev_delayed_handler(void *param)
+virtio_user_dev_delayed_disconnect_handler(void *param)
 {
 	struct virtio_user_dev *dev = param;
 	struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
@@ -894,14 +895,27 @@ virtio_user_dev_delayed_handler(void *param)
 		PMD_DRV_LOG(ERR, "interrupt disable failed");
 		return;
 	}
-	rte_intr_callback_unregister(eth_dev->intr_handle,
-				     virtio_interrupt_handler, eth_dev);
+	PMD_DRV_LOG(DEBUG, "Unregistering intr fd: %d",
+		    eth_dev->intr_handle->fd);
+	if (rte_intr_callback_unregister(eth_dev->intr_handle,
+					 virtio_interrupt_handler,
+					 eth_dev) != 1)
+		PMD_DRV_LOG(ERR, "interrupt unregister failed");
+
 	if (dev->is_server) {
 		if (dev->ops->server_disconnect)
 			dev->ops->server_disconnect(dev);
+
 		eth_dev->intr_handle->fd = dev->ops->get_intr_fd(dev);
-		rte_intr_callback_register(eth_dev->intr_handle,
-					   virtio_interrupt_handler, eth_dev);
+
+		PMD_DRV_LOG(DEBUG, "Registering intr fd: %d",
+			    eth_dev->intr_handle->fd);
+
+		if (rte_intr_callback_register(eth_dev->intr_handle,
+					       virtio_interrupt_handler,
+					       eth_dev))
+			PMD_DRV_LOG(ERR, "interrupt register failed");
+
 		if (rte_intr_enable(eth_dev->intr_handle) < 0) {
 			PMD_DRV_LOG(ERR, "interrupt enable failed");
 			return;
@@ -909,6 +923,32 @@ virtio_user_dev_delayed_handler(void *param)
 	}
 }
 
+static void
+virtio_user_dev_delayed_intr_reconfig_handler(void *param)
+{
+	struct virtio_user_dev *dev = param;
+	struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
+
+	PMD_DRV_LOG(DEBUG, "Unregistering intr fd: %d",
+		    eth_dev->intr_handle->fd);
+
+	if (rte_intr_callback_unregister(eth_dev->intr_handle,
+					 virtio_interrupt_handler,
+					 eth_dev) != 1)
+		PMD_DRV_LOG(ERR, "interrupt unregister failed");
+
+	eth_dev->intr_handle->fd = dev->ops->get_intr_fd(dev);
+
+	PMD_DRV_LOG(DEBUG, "Registering intr fd: %d", eth_dev->intr_handle->fd);
+
+	if (rte_intr_callback_register(eth_dev->intr_handle,
+				       virtio_interrupt_handler, eth_dev))
+		PMD_DRV_LOG(ERR, "interrupt register failed");
+
+	if (rte_intr_enable(eth_dev->intr_handle) < 0)
+		PMD_DRV_LOG(ERR, "interrupt enable failed");
+}
+
 int
 virtio_user_dev_server_reconnect(struct virtio_user_dev *dev)
 {
@@ -974,18 +1014,14 @@ virtio_user_dev_server_reconnect(struct virtio_user_dev *dev)
 			PMD_DRV_LOG(ERR, "interrupt disable failed");
 			return -1;
 		}
-		rte_intr_callback_unregister(eth_dev->intr_handle,
-					     virtio_interrupt_handler,
-					     eth_dev);
-
-		eth_dev->intr_handle->fd = dev->ops->get_intr_fd(dev);
-		rte_intr_callback_register(eth_dev->intr_handle,
-					   virtio_interrupt_handler, eth_dev);
-
-		if (rte_intr_enable(eth_dev->intr_handle) < 0) {
-			PMD_DRV_LOG(ERR, "interrupt enable failed");
-			return -1;
-		}
+		/*
+		 * This function can be called from the interrupt handler, so
+		 * we can't unregister interrupt handler here.  Setting
+		 * alarm to do that later.
+		 */
+		rte_eal_alarm_set(1,
+			virtio_user_dev_delayed_intr_reconfig_handler,
+			(void *)dev);
 	}
 	PMD_INIT_LOG(NOTICE, "server mode virtio-user reconnection succeeds!");
 	return 0;
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h b/drivers/net/virtio/virtio_user/virtio_user_dev.h
index 8a62f7ea79..15d177ccd2 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
@@ -78,7 +78,7 @@ uint8_t virtio_user_handle_mq(struct virtio_user_dev *dev, uint16_t q_pairs);
 int virtio_user_dev_set_status(struct virtio_user_dev *dev, uint8_t status);
 int virtio_user_dev_update_status(struct virtio_user_dev *dev);
 int virtio_user_dev_update_link_state(struct virtio_user_dev *dev);
-void virtio_user_dev_delayed_handler(void *param);
+void virtio_user_dev_delayed_disconnect_handler(void *param);
 int virtio_user_dev_server_reconnect(struct virtio_user_dev *dev);
 extern const char * const virtio_user_backend_strings[];
 #endif
-- 
2.26.2